1. Field of the Invention
The invention relates to a method for fabricating an organic electroluminescent device (OLED), and more particularly to a method for fabricating a carbon-enriched film with high conductivity and a method for fabricating an organic electroluminescent device (OLED) employing the carbon-enriched film as the buffer layer thereof.
2. Description of the Related Art
Display serving as an interface between human and information plays a significant role in everyday activities. Currently flat panel displays have become the major trend in the display field. Wherein in particular, an organic electroluminescent display has enormous potential and is expected to become the main stream of the next generation flat panel displays, thanks to its predominant advantageous features, such as self-emitting, no viewing angle dependency, power-saving, simpler process, low-cost, lower operation temperature range, fast response and full colorization.
An organic electroluminescent display mainly takes advantage of the self-emitting nature of an organic electroluminescent device (OLED) to achieve displaying effect. Wherein, the organic electroluminescent display mainly comprises a pair of electrodes and an organic layer. When current flows between the anode and the cathode, electrons and holes in the organic layer are recombined to produce excitons and enables the organic layer to produce lights with different colors depending on the material property of the organic layer. Thus, a luminous display is achieved.
FIG. 1 is a schematic view of a structure of a conventional organic electroluminescent device (OLED). Referring to FIG. 1, a conventional OLED 100 includes a substrate 110, an anode layer 120, a hole transporting layer (HTL) 130, an organic electroluminescent layer (OEL) 140, an electron transporting layer (ETL) 150 and a cathode layer 160. As an offset voltage is applied between the anode layer 120 and the cathode layer 160, electrons are injected into the electron transporting layer (ETL) 150 from the cathode layer 160 and are transmitted to the organic electroluminescent layer (OEL) 140, while holes are injected into the hole transporting layer (HTL) 130 from the anode layer 120. Further, the injected holes are transmitted to the organic electroluminescent layer (OEL) 140, where the electrons and the holes are recombined to generate excitons and produce luminous effect.
The anode layer 120 is typically comprised of an indium tin oxide (ITO) material, and therefore the contact interface between the ITO (an inorganic material) and the hole transporting layer (HTL) 130 (an organic material) has a poor electrical contact. In order to resolve the above problem some proposed suppressing the switching current by treating the surface of the ITO anode layer with an UV-ozone and a plasma. However, exposure of the surface of the anode layer 120 to the UV-ozone and plasma may damaged the surface of the anode layer 120, which may adversely affect electrical properties of the anode layer 120.
Some others propose disposing a buffer layer (not shown) between the anode layer 120 and the hole transporting layer (HTL) 130. However the conductivity of the buffer layer is poor, which lower the luminous efficiency of the organic electroluminescent device (OLED) 100.